The present invention relates to a method and apparatus for automatically controlling an activity of a developing liquid, for use in a developer.
In a conventional automatic developer, an apparatus for automatically controlling an activity of a developing liquid supplies a supplemental developing liquid of the corresponding amount to the blackening area of a photographic printing paper, film, or the like, developed after the start of the operation. In this embodiment, the concentration of the supplemental developing liquid, its supplying volume by one operation, and the one supplementing time are fixed, and this supplement is started by a supplement signal so as to control the interval of every supplement when the blackening area of the film becomes a fixed value, thereby controlling the activity of the developing liquid in a certain range.
Hence, when films having a large blackening area are processed continuously, the blackening area is raised to the fixed value to output the supplement signal in a short time. However, when the supplement signal is output during the supplement of the supplemental developing liquid, this signal is ignored and becomes ineffective, with the result of the depression of the activity under the standard value.
When the concentrated supplemental developing liquid is supplied rapidly in order to avoid such a problem, the activity of the developing liquid becomes uneven, and the volume of every supplement becomes incorrect.